ModuleNotFoundError: No module named 'telnetlib' — removed in Python 3.13; use telnetlib3, Exscript or a backport

• Preferred (from the 3.13 What's New): "Use the telnetlib3 or Exscript libraries from PyPI instead." telnetlib3 is asyncio-based, so calling code changes:

# before
import telnetlib
tn = telnetlib.Telnet(host, 23); tn.read_until(b"login: ")

# after
import asyncio, telnetlib3
async def main():
    reader, writer = await telnetlib3.open_connection(host, 23)
    print(await reader.readuntil(b"login: "))
asyncio.run(main())

• Drop-in stop-gap: a copy of the old module is on PyPI as telnetlib-313-and-up (pointed to by the Robot Framework maintainer); keep import telnetlib unchanged.
• If the device supports it, move to SSH (paramiko/netmiko).